Once candidates start "testing the waters" of a presidential campaign, they cannot raise more than $2,700 from an individual donor for the nomination battle. Each of the likely candidates targeted by watchdogs is aligned with a fundraising committee that can accept contributions larger than $2,700. ...

"These 2016 presidential candidates must take the American people for fools — flying repeatedly to Iowa and New Hampshire to meet with party leaders and voters, hiring campaign staff and raising millions of dollars from deep-pocketed mega donors, all the while denying there are even 'testing the waters,' " said Paul Ryan, the legal center's senior counsel.

Ryan said more complaints are on the way. ...

As the Center for Public Integrity's Dave Levinthal notes, several complaints filed against 2012 presidential candidates still are pending today.